Circuits for tracer controlled machine tools



Feb. i3, 1948o J. J. JAEGER 2,435,280

CIRCUITS FOR TRACER CONTROLLED MACHINE TOOLS Fiied June 28, 1943 2 sheets-sheet 1 Zlll `f u J. J. JAEGER 2,435,280

CIRCUITS FOR TRACER CONTROLLED MACHINE TOOLS Filed June 28, 1943 2 Sheets-Sheet 2 Patented Feb. 3, 19,48

GIRCUE'IS` FOR TRACER CONTROLLED MACHINE TOOLS Jacob d. Jaeger, West Hartford, Conn.,

to Niles-Bement-Pond Gompany,

assignor West Hartford, Conn., a corporation or New `Hersey Application .lune 28, 1943, Serial No. 492,543 4 Claims. (Cl. 1952-84) This invention relates to tracer controlled electrically operated machine tools and particularly to improved operating means for the clutch magnets of a form turning lathe, copying milling machine, or similar machine tool.

A primary object oi the invention is to provide improved circuits controlling the energization of clutch operating electromagnets so that their speed of operation in starting and stopping movements of machine slides controlled thereby may be increased.

A feature of importance of the invention is that the clutch magnets are initially energized with a high potential and thereafter the potential is substantially reduced, the potential remaining after this reduction being sufficient to hold the clutch engaged so that movement of the slide operated thereby may be continued, and, when the reduced potential circuit for a clutch magnet is opened to release the clutch, the time of release of the clutch is substantially decreased to stop further movement of said slide and prevent overtravel.

Another feature of importance is that the clutch magnet energizing circuits are controlled through relays, one of which serves to energize a magnet with full line potential; and a second relay, operated mornentarilyafter the first relay, controls the holding circuit for the clutch magnet at a reduced potential.

The invention has been illustrated as embodied in a machine of the type shown and described in the patent to Shaw 1,711,290, granted April 30, 1929, and the present invention will be described in connection with the circuits shown in that patent for controlling movements of a tool carriage and cross slide. It will be understood, however, that the invention may be employed in other types of machine tools in which movements of the tool relative to the work are controlled by a contact closing tracer following a pattern or template and in which -the means for moving the tool include rotating clutch magnets coupled when energized as indicatedin the above-referred to patent to drive lead screws or other actuating means for the movable slides of the machine.

In general, therefore, it is a primary object of the present invention to increase the speed of operation of clutch magnets controlling movements of machine tool slides by reducing the holding voltage of its coil after initially energizing the coil with full potential, the energizing potential causing extremely rapid engagement of a clutch and the reduced holding voltage being suiiicient, after the clutch has been engaged, to continue to hold the clutch engaged under any load that may be initially started by the clutch at full potential.'

lOther objects and advantages will be apparent from the specication and claims, and from the drawings, which illustrate what is now considered to be a preferred embodiment of the invention.

In the drawings annexed hereto and forming a part of this specification: l l

Figure 1 is a front elevation of an engine lathe to which the present invention may be` applied, parts being shown in section to more clearly show their construction.

Fig. 2 is a p lan view of the machine shown in Fig. l, several parts being shown in section.

Fig. 3 is a fragmentary cross-sectional View of the machine shown in Figs. 1 and 2, and

Fig. 4 is a diagram of the electric circuits for the clutch operating magnets.

In its preferred form, the invention may include the following principal parts: First, a machine tool such as an engine lathe shown in the drawings as having tool slides mounted one on the other for movements at right angles to each other: second, magnetic clutches for actuating each of 'the slides in either direction; third, a pattern or template supported in iixed position on the machine; ourth, a tracer movable with said slides over a surface of said pattern or template; fifth, relays operated by contacts on said tracer controlling circuits for said clutches; sixth, a supplemental relay controlled by operation oi' either of theiirst mentioned relays so that the supplemental relay operates after either of said rst relays operates; and seventh, supplemental clutch magnet circuits having a reduced potential compared to the first clutch magnet circuits, said supplemental magnet circuitsbeing controlled by said supplemental relay.

Referring more in particular to the figures of the drawing, the lathe comprises the usual bed i having a headstock 2 at one end within which is mounted a work rotating spindle 3. A carriage it is provided which may be moved to the left or right along the bed l by means of a suitable lead screw 1. Lead screw l is connected through suita movements of the carriage 6 may be reversed. orv` by breaking a clutch magnet circuit, movement of the carriage 8 will be stopped.

The carriage 3 is provided with a cross slide I1 carrying a tool holder I8 and is adapted to be operated to move the tool I9 directly toward or from the work. To effect movement of this cross or tool carrying slide I1 there is provided a transverse lead screw 20. The cross feed screw 20 may be manually operated in the usual manner and, in addition is connected by means of bevel gears 22 to a shaft 23 adapted to be driven by either of a pair of magnetic clutches I2 provided in a suitable clutch housing 24 supported upon the tool carriage 6 so as to travel therewith. The two clutches I2 in the housing 24 are similar to clutches I for longitudinally moving the carriage 6 so that when oneclutch I2 is energized the tool moves in and when the other clutch I2 is energized the tool moves out The work being turned may be held between centers in the usual manner and may be rotated at any desired speed, movement of the carriage B by lead screw 1 driven from the spindle 3 through clutches I0 being at all times proportionate to the rotation of the work.

The cross slide I 1 is provided with a bracket or arm 30 the outer end of which supports a contact tracer 3|, the tracer point `32 of which is adapted to engage a pattern or template 33 corresponding in outline to the work being operated on. The pattern or template 33 is mounted in fixed position and may be directly supported on a suitable bracket 34 secured to the lathe bed I. Thus it will be seen that by having the tracer 3l follow the pattern and by having tracer 3| control the movements of the respective lead screws 1 and 2D through the magnetic clutches I0 and I2 the cross slide and the lathe tool will be moved toward or from the axis of the work.

during traversing movement of the slide 6 to the left or right along the lathe bed I and will reproduce the form or outline of the template thereon. In this mechanism the tracer 3i controls the in and -out" movement of the lathe tool by controlling circuits for the magnetic clutches I2 operating the transverse screw 2U, and when movement of the tool I9 in or out occurs the traversing movement of slide 6 is interrupted. This control of the magnetic clutches through the tracer 3| will be further referred to in connection with the wiring diagram.

The magnetic clutches ID for operating the longitudinal lead screw 1 are indicated in the Wiring diagram, Fig. 4, as E and W, and the magnetic clutches I2 for operating the transverse screw 20 are indicated respectively by in" and out The tracer 3| is indicated diagrammatically and may be similar to that shown in patent to J. C. Shaw 1,518,114, granted December 2, 1924. -The tracer and tracer point form no part of the present invention and will be referred to only briefly. y

The tracer point 32 is adapted to actuate the contact carrying lever 39 pivotally mounted within the head of the tracer body 3| whenever the tracer point touches the work. This lever carries a contact 42 cooperating with an adjustable contact 43 at the'y end of an insulated screw in the bracket plate 46 supported on the tracer` body 3l. The tracer body 3i is grounded, as indicated, so that an electric circuit may be completed through the contacts 42--43 and lever 39.

A tension spring 48 and a compression spring 49 are adapted to draw the upper end of the lever outward to normally hold the in contacts 42-43 closed. Normally, the tool I9 travels in or toward the work until the tracer point 32 also moving "in" therewith is tilted by contact with the pattern.

The pivotally mounted lever 39 also carries a contact 50 on the opposite side from contact 42 which is adapted to cooperate with an adjustable contact 5I on an Iadjusting screw 62 suitably insulated and mounted on a lever 54 pivoted to the tracer body 3l but insulated completely therefrom. A compression spring and suitable adjusting screws are provided for holding the lever 54 toward the upper end of the iirst mentioned lever 39, but the forward or normal position of this auxiliary lever 54 is limited by an adjusting screw 59, the end of which carries a contact 60 cooperating with a contact 6I on the upper end of the lever 54. The adjusting contact screw E9 is as shown insulated and is mounted in the bracket plate 46.

It will be seen from the wiring diagram that the normally closed circuit through contacts 42-43 energizes the solenoid of the triple pole in" relay, which'is shown unenergized. This circuit from the grounded tracer extends through lever 39, contacts 42-43, lead 63, the in" relay, and lead 61 to a grounded generator 68. Energlzing of the in relay simultaneously closes two circuits and opens a third circuit. The opened circuit extends from line wire 13 to the contactor 1I, lead 13, tracer contacts GII-6I, lead 14 to one or the other of E W clutches, whichever is being used, and lead 15 to line wire 16. As soon, therefore. as in relay is energized, movement of the carriage 6 stops.

Closing of contactor 11 by the energized in" relay starts the tool I9 moving toward the work, this circuit from line wire 10 includes lead 18, contactor 11, lead 19 to the in clutch, and lead directly to the line wire 16. Closing of contactor 8| bythe in relay energizes a supplemental relay 82 and the energizing of this relay 82 involves a slight lapse of time following the closing of contactor 8|, this circuit including grounded generator 68, lead 61, contactor BI, lead 83 to relay 82 to ground. The function of supplemental relay 82 which is shown de-energized, will presently be described.

- When the tracer point 32 strikes the pattern, contacts 42-43 are opened; this will de-energize the in relay. De-energizing the in relay into the position shown in Fig. 4 opens the circuit to the in clutch, opens the circuit to the supplemental relay 82 and simultaneously closes the circuit to the E or W clutch, whichever has been selected by the manual switch 92.

'I'he carriage will then move along the bed i until the shape of the pattern or template causes the tracer point 32 to move a suiiicient distance to close either the contacts 42-43 if the pressure is eased, or the contacts Sil- 5I if the pressure is increased. Closing the contacts 42-43 will repeat the operation described above. Closing the contacts Sii-5I will energize the out relay, the circuit including the grounded tracer 3 I, lever 39, contacts' SII-5I, lead 85, out relay, Alead 61, and the grounded generator 68.

Energizing the "out relay closes the circuit to the "out clutch, closes the circuitto the supplemental relay 82, and simultaneously opens the circuit to the E or W" clutch.

From the above it will be seen that closing tracer contacts 42-43 or .5U-5I causes the operation of the supplemental relay 82, and, as the circuit for operating this supplemental relay includesv contacts controlled by the in or "out" relay, relay 82 is'not energized until after the "in or out relay has been energized. Supplemental relay 82, when energized, opens one normally closed contact and closes another contactor which is normally open.

A moment after the in or out relay, which constitute individual principal electrical means for the clutches, is energized the supplemental relay 82 is'energlzed and opens the circuit from line wire 18 through contact 81 to the lead 80. With contact 81 open, the circuit from line wire 'I8 to lead 80 must traverse resistance 88, thus reducing the potential applied to hold the "in" or out clutch, whichever is operating. Energizing relay 82 also closes contact 90and cuts out resistance 9| from the circuit to the E or W clutch magnet so that when one o! these latter magnets is again energized it will be at the full potential of the line. ing at full potential continues momentarily after the in or out relay opens, as supplemental This energizrelay 82 cannot release until after the in or v out relay releases. As .soon as supplemental relay 82 has been de-energized, contact 9B will open and resistance 9| will then be included in the E or "W clutch magnet circuit, so that these clutches are initially energized with the full# potential of the line and are held in engagement with a reduced potential similar to the in and out clutches.

It will be seen that a manual selector switch 92 enables the E or W clutch to be used for the normal or leading movement of the tool along the lathe bed i.

What I claim is:

1. In a device controlled by a plurality of electromagnetic clutches, principal electrical means for each of said electromagnetic clutches connected for applying thereto a predetermined initial voltage, individual control means for controlling such application of each of said electrical means, and a single supplemental time delay electrical means connected to both of said principal electrical means adapted to substantially reduce the magnitude of the voltage maintained applied by said one principal electrical means to its clutch a predetermined time after the application thereto of said initial voltage independent of other conditions, whereby pick-up time and releasing time and overtravel are reduced.

2. In a device controlled by a plurality of electromagnetic clutches, principal electrical-means for each of said electromagnetic clutches connected for applying thereto a predetermined initial voltage, individual control means for controlling such application of each of said electrical means. and supplemental time delay electrical means connected respectively to both of said principal electrical means adapted to substantially reduce the magnitude of the voltage maintained applied respectively by each of said two electrical means to its respective clutch a. predetermined time after the application to the respective clutch of said initial voltage independent of other conditions, whereby pick-up time and releasing time and overtravel are reduced.

3. In a device controlled by a plurality of electromagnetic clutches, principal electrical means for each of said electromagnetic clutches 'connected for applying thereto a predetermined initial voltage, individual control means for controlling such application of each of said electrical means, and supplemental time delay electrical means connected to both of said principal electrical means adapted to substantially reduce the magnitude of the voltage maintained applied by said one principal electrical means to its clutch a predetermined time after the application thereto of said initial voltage independent of other conditions, said supplemental means being actuatable by said individual control means through the said principal electrical means, whereby pickup time and releasing time and overtravel are reduced.

4. In a device controlled by a plurality of electromagnetic clutches, a source of electrical power, principal relay means having a rst set of controlled contacts connected between said source and said one clutch, said relay means further having a second set of controlled contacts connected between said source and another clutch,

said relay means and its connections being adapted to selectively complete connections from said clutches to either of said sets of contacts but not to both, supplemental relay means connected for actuation a predetermined time after the actuation of said principal relay means independent of other conditions and having controlled contacts, individual resistors for the energizing circuits of each of said clutches respectively, connections between said resistors respectively and said controlled contacts of said supplemental relay means and the energizing circuits of said clutches for respectively inserting each of said resistors in series in the energizing circuit of each of Asaid clutches respectively upon energization or de-energization of said supplemental relay means after said predetermined time delay.

and switch means connected to actuate said principal relay means.

JACOB J. JAEGER.

, REFERENCES CITED The following references are of record in the ille of this patent:

'UNITED STATES PATENTS Number Name Date 727,641 Knowlton May 12, 1903 727,689 Reist May 12, 1903 761,459 Eastwood May 31, 1904 799,720 Cutler Sept. 19, 1905 1,142,852 Simon June 15,1915 1,601,791 Bing Oct. 5, 1926 1,671,057 Brainard May 22, 1928 1,711,29() Shaw Apr. 30,1929 1,815,152 Klotz July 2l, 1931 1,915,566 Younghusband June 27, 1933 2,257,361 Yorkey Sept. 30, 1941 

